解方程.(带*的要验算)*15x-33=42 5x+2.6×5=25 13x-5x=32.8&nb...

解方程.(带*的要验算)*15x-33=42 5x+2.6×5=25 13x-5x=32.8 4x-89=19.
2025-06-20 19:59:50
推荐回答(1个)
回答1:

(1)15x-33=42
     15x-33+33=42+33
           15x=75
             x=5
   验算:把x=5代入方程的左边,
左边=15×5-33=75-33=42
左边=右边
所以x=5是原方程的解.

(2)5x+2.6×5=25    
         5x+13=25
      5x+13-13=25-13
            5x=12
             x=2.4

(3)13x-5x=32.8
         8x=32.8
      8x÷8=32.8÷8
          x=4.1

(4)4x-

8
9
=
1
9

  4x-
8
9
+
8
9
=
1
9
+
8
9

       4x=1
        x=
1
4